A photon pair source based on nonlinear waveguides was used to investigate fluorescence excitation of quantum dots. We present a comprehensive study of entangled absorption behavior by varying experimental quantities and following latest theoretical insights.
Entangled Two-Photon Absorption The front cover illustrates the fluorescence excitation of quantum dot molecules by absorption of entangled photon pairs. The so-called entangled two-photon absorption is highly affected by the generation of these photon pairs. In article number 2300037, Tobias Bernd Gäbler and co-workers describe the important properties of an ultra-bright photon pair source based on nonlinear waveguides and its usage to approach fluorescence excitation. (Image designed by Christian Süß).
Abstract Fluorescence excitation by absorption of entangled photon pairs offers benefits compared to classical imaging techniques, such as the attainment of higher signal levels at low excitation power while simultaneously mitigating phototoxicity. However, current entangled photon pair sources are unreliable for fluorescence detection. In order to address this limitation, there is a need for ultra‐bright entangled photon pair sources. Among the potential solutions, sources utilizing nonlinear waveguides emerge as promising candidates to facilitate fluorescence excitation through entangled photons. In this paper, a source consisting of a periodically poled lithium niobate waveguide is developed and its key characteristics are analyzed. To demonstrate its suitability as key component for imaging experiments, the entangled two‐photon absorption behavior of Cadmium Selenide Zinc Sulfide quantum dot solutions is experimentally investigated.